Apparatus for evaporating cement slurry



Jan-QA, 1933.4 Q M11-TAG 1,895,201

APPARATUS FOR EVAPORATING CEMENT SLURRY Filed Deo. 8, 1930 2 Sheets-Sheet 2 /N VEN TOR CARL MWA@ ATTORNEY Patented Jan. 24, 1933 UNITED' STATES PATENT Y' OFFICE CARL MITTAG, OF' MAGDEBURG, GERMANY, lASSIGNOR TO THE AFIRM FRIVED. XBUPI GBUSONWERK AKTIEN GESELLSCHAFT, F MAGDEBURG-BUCKAU, GERMANY APPARATUS FOR. EVAIORATING CEMENT SLUBRY appucaaon mea December s, 1930, serial No.

My invention relates to improvements in the manufacture of cement and like artificial hydraulic mortars, and more especially to improved means for evaporating, drying and thickening cementslurry,-i. e. a watery or semi-liquid mixture of powdered raw materials,-.-prior to burnin the latter 1n a kiln,- the principal object o evaporating the sl ur ry being to shorten and enhance the burning process and to achieve a substantial saving of fuel.

It is known in the art of manufacturing cement to utilize the heat of the combustion gases issuing from the cement kiln for evap- 16 orating the slurry. v

In the olden times-more than half a century agothe wet slurry was simply spread out on the bottom of elongated iiues or chambers through which the combustion gases 20 were conducted on their way to the chimney,

until the slurry was dried, in most cases representing a rather hard cake, the removal of which from the said chamber and comminution into small bricks involved considerable work and delay.

In more recent times slurry chambers have become known which are structurally combined with or directly attached to the feeding end of a cement kiln of the tubular rotary 3o type, the object of said arrangement being to expose a continuousfcurrent of the wet slurry in iinely divided condition to the hot combustion gases near the 'point Where the latter issue from the kiln. Various atomi zing' methods and means are used for finely divid.

ing the slurry in saidA chambers, such as sprayin apparatus through the nozzles of which t e slurry is forced under pressure, or rapidly rotating discs dipping into the slurry 40 and reducing the latter to a spray by centrifugal force.

However these methods of evaporating the slurry by transforming it into a spray and subjecting the latter to the action of the fiue gases involves considerable disadvantagesknown to practitionersalso in as much as a substantial proportion of the atomized slurry f is becoming overdried with the result that` itis carried oi'l' in pulverlent form-as dust-- wlth the flue gases and is thus lost, unless be- 500,958, and in Germany December'21, 1829.

course ofthe evaporation a substantial pro-- portion of the pulverulent cement suspended in and carried ofi' by the hot combustion gases issuing fromithe cement kiln.

Further objects of the invention and advantages obtained thereby will become apparent hereinafter.

The-nature and scope of this invention are briefiy outlined in the appended claims and will be more fully understood from the following specification, taken together with the accompanying drawings in which a few typical embodiments of the invention are shown by Way of examples: V

vFig. l is a section, longitudinally taken through a slurry chamber designed for con I ditioning the slurry according to this invention for the .subsequent burning process.

Fig. 2 is a cross section through the slurry chamber, taken on line II-VII of Fig. 1,

Fig. 3 is a diagrammatic layout *showing a complete slurry treating plant and its cooperative connection with a tubular rotary cement kiln and with a heat recovering boiler lant,

ig. 4 is a plan view of the slurry chamber prper of Fig. 3, igs..5-7 are sectional views, diagrammatically showing other types of slurry treating chambers designed according to this invention, f

Fig. 8 is a cross section through a. set of I rotary discs of modified design, which may be used to advantage in any of the slurry treating chambers shown in Figs. 1-7.

,One of the salient ideas of my invention is the employment` of slowly rotating discs, adapted to spread out the slurry into 'relatively thin layers and to expose the latter to the hot gases which issue from the cement kiln and which, by coming into intimate contact with the finely spread out slurry for a considerable length of time will effectively preheat and evaporate the latter.

Referring first to the simplestforni of my improved slurry treating plants, as shown in Figs. 1 and 2, 10.-' designates the flue of the cenrent kiln, throughwhich the hot combustion lgases pass on their way to the chimslurry receiving tank 12 is attachedto the bottom of said Hue, through which a rotary shaft 32 extends transversely, carrying a plurality of discs 30, the latter being spaced from each other and dipping into the slurry, which is supplied into the tank 12-through a pipe-not shown-or other convenien feeding means known per se.

On revolving the discs 30 in the direction of arrow -e. g. by a worm gear 37,38, attached to shaft 32, thin layers of the slurry adhering to the discs are continuously lifted upward right into the path of the hot flue gases and are thus exposed to thelatter.

At the same time pulverulent cement which is usually suspended as dust in thel iiue gases is recovered by being caught at the wet surfaces of the discs 30 and is incorporated'into the slurry.

Stripping blades 35-preferably having openings in their middle--are provided for stripping from the discs 30 the thickened slurry, as indicated in Fig. 1 which is thereupon drawn off through `pipe 16 and -is charged in its preheated condition into the cement kiln.

In addition to means such as valves-.notl

shown-but-known per se, for controlling the supply of the slurry to tank 12 andthe discharge of the slurry from the latter, a drain pipe 14 is provided acting as an overflow and insuring the slurry tank to be filled up to a certain level.

The thickened and preheated slurry drawn oli?` through pipe 16 may be subjected to subsequent treatment in one or more chambers of the type shown in Figs. l and 2.

A slurry treating plant of modified design and larger capacity is shown in Figs. 8 and 4 and comprises tw sets of rotary discs 30a and 30?), cooperatively arranged` in slurry tank 12a in staggered position to each other so asfto partly overlap each others ieldot action. A

The discs are slowly rotated in the direction of arrows and u by gear wheels 37a,

37b, 38a, the thickenedv slurry being stripped oil by blades 35a, 355 a'udbeing forcibly discharged by a worm conveyor 40 into the intake .end of -a rotary cement kiln through pipe 16a.

Valves, such' as revolvable and sliding check plates 51, 52, 53, 54` 55 are rovided for controlling the path of travel o the hot iiue gases. The latter Vgenerally issuing from the cement kiln in the direction of arrow a' first pass through the iiue proper 10, including the slurry treating chamber, and thence through the furnace of a heat recovering boiler plant 60. In cases of emergency the hot gases or part thereof may be'discharged directly into the chimney by turning valve plates 51,52, 53, 54, 55 into their opened and closed positions respectively.

l Another modified type of slurry treating chambers designed for evaporating the slurry in two stages, is shown by way of an example in Figs. 5 and 6, comprising two sets of rotary discs 300, 30d which are cooperatively arranged at some distance from each other in slurry tank 120 and are slowly rotated in the direction of arrows u by gear wheels 37e, 37d', 38?).

The wet slurry is supplied through a pipe 140. After having been first exposed by the discs 30d to the hot gases passing through flue l() in the direction of arrow the slurry is returned by the stripping blades 35d into the tank 12o in which it is remixed with the wet slurry by rotary agitating arms 70.

.Thereupon the lslurry is exposed for a second time; to the hot combustion gases by the 'discs 2.00 and is then delivered over the stripdiscs 30f, both sets of discs rotating in thev direction of arrowsu, u. Stripping blades 35e and 35] are provided for delivering the evaporated slurry into worm conveyors 40e, 407, the latter being interconnected with each other and with the cement kiln respectively through pipes 14f and 16.. f

Various other changes and modifications may be made in the design of the slurry treating plants vdescribed above and. in the shape and cooperation of. their component vparts, without substantially departing from the salient ideas of this invention and sacrificing any advantages obtained thereby.

E. g. discs 30a of undulated or corrugated cross sectionas shown in Fig. S-may be used to advantage in any of the slurry treating plants designed in accordance with this invention-instead of plain discs-in connec- ,to' the top of said Hue,

tion with stripping shape.

What I claim is: I l, The combination with a kiln of a Hue structure communicating therewith, a slurry evaporating plant within said Hue structure comprising a tank at the bottom of said Hue, a plurality of rotatable disks mounted on an axis transverse to the Hue and extending from substantially the bottom of said tank said vdisks being spaced axially from one another forming a p urality of, narrow channels therebetween through which the gases of combustion from said kiln have to pass to escape from said 2. The combination with a rotary kiln of a Hue structure communicating therewith, a slurry evaporating plant within said `Hue comprising a plurality of rotatable disks extending across said Hue, spaced axially from one another and forming a plurality of narrow channels through which the gases 0f combustion from said kiln have to pass.

3. The combination wwith a kiln of a Hue structure communicating therewith, a slurry evaporating plant within said Hue comprising atank at the bottom of said Hue, a plurality of rotatable disks having their lower portion within said tank and extending to substantially the top of said Hue, said'disks being spaced from one another to form a plurality of relatively narrow channels through which the exhaust gases from said kiln have to pass.

4. The combination with a kiln of a fine blades of corresponding structure communicating therewith, a slurry ,v evaporating plant within said Hue comprising a slurry tank at the bottom of said Hue, a plurality of rotatable disks mounted on an axis transverse to said from substantially the bottom of said tank to the top of said Hue, said disks being axially spaced from one another to form a plurality of narrow channels through which the gases o-f combustion have agitating the slurry within said tank.

5. The combination with a kiln of a Hue structure communicating with said kiln, a

slurry evaporating plant within said Huecomprising a slurry tank at the bottom of said Hue, a plurality of rotatable disks mounted on' an axis transverse to said Hue and extending 1 from within said tank to substantially the top of said Hue,means for feeding fresh slurry into said tank and means for conducting the ifgflaporating slurry from said tank to said 6. The combination with a kiln of av Hue structure communicating with said kiln, a slurry evaporating plant within said Hue comprising a slurry tank at the bottom of said Hue, a plural-ity of rotatable disks mounted on an axis transverse to said Hue and extending from within said tank to substantially Hue and extending to pass, and means for the top of said Hue, means for feeding fresh slurry into said tank and means for conducting the evaporated slurry from said tank to said kiln, and means within said tank for agitatingthe slurry within said tank.

7. The combination with a kiln of a Hue structure communicating therewith, of a slurry evaporating plant within said Hue structure comprising slurry tanks located at the bottom of said Hue, a plurality of sets of rotatable disks mounted on axes transverse to said Hue, said disks extending into said tanks and into said Hue structure, said disks of each set being axially spaced from one another to form a plurality of relatively narrow channels through which the gases of combustion from said kiln have to pass, means for feeding fresh slurry into one of said tanks, means for feeding partially evaporated slurry from said tank into the second tank, means for conveying the evaporating slurry from said second tank to said kiln.

8. The combination of a slurry evaporating tank and a Hue structure communicating therewith, of a slurry evaporating plant located within said Hue structure comprising a plurality of rotatable disks mounted on an axis transverse to said Hue, said disks beingaxially spaced one from another to form a plurality of narrow channels through which the gases of combustion from said kiln have to pass, and stripping blades associated with said disks for removing the evaporated slurry from said disks.

9. A combination with a kiln of a Hue structurecommunicating therewith, a slurry evaporating plant within said Hue comprising a tank 4located at the bottom of said Hue, a plurality of rotatable disks mounted on an axis transverse to said Hue, said disks extending into said tank and to substantially the top of said Hue structure, stripping blades assou ciated .with said disks for removing the evaporating slurry therefrom, and agitating means within said tank for agitating the slurryV within said tank.-

10. The combination with a kiln of a Hue I' signed my 

